Helical gear units provide an alternate method of connecting parallel shafts. They are suitable for machines with higher speed ranges, low noise levels, and less vibrations. These gear units can also be used for applications in the pump industry, refineries, and paper industries.

Helical gear units are typically available in three drive solutions: NORD standard, foot/flange mounted, and radial type. All three solutions feature proven quality and offer a wide range of applications. The helical gear units are manufactured from case hardened steel and can be customized to meet special requests.

Thin rimmed helical gears are available in both symmetric and asymmetric web arrangements. The root stresses of these gears were determined using a strain gage measurement method. Typical helix angles vary between 15 to 30 degrees. Various effects of rim and web thicknesses were examined, as well. Using these methods, changes in the root stress were correlated with the worst meshing position. For symmetric helical gears with a helix angle b0 = 20deg, bending fatigue limits were determined.

Helical gear units are commonly used in automotive transmissions, on machinery with high torque transmission, and in industries that require lower sound levels. Their main advantage is that they are more robust than spur gears. However, their disadvantages include lower efficiency, higher friction, and increased wear. A helical gear unit is best combined with an AC motor to eliminate directional errors.

When compared to spur gears, helical gears are more surface touching, which allows several teeth to mesh at once. This improves load-carrying capacity, though it can lead to higher contact pressures. While helical gears are advantageous in reducing vibrations, they are not as effective as spur gears at translating large forces.

Helix angle is a major factor in determining the effectiveness of helical gears. As a general rule, helix angle is on either side of the gear centerline. In contrast, a spur gear has a single helix angle that is the same in both directions. On the other hand, cross-axis gears have no helix angle, and therefore, do not carry axial thrust.

Cross-axis helical gears are a very basic type of helical gear. They have a perpendicular orientation to the axis of rotation. During the meshing process, the angled teeth create a thrust load on the gears. Depending on the magnitude of the tangent of the helix angle, the thrust load varies from zero to a significant amount.

Helical gears are classified by their reference section in a standard plane. Spur gears and helical gears with a standard plane reference section have the same center gap. Therefore, they can be swapped for each other. By applying a spur gear hobbing tool, a helical gear can be converted to a spur gear.

The cross-axis helical gear is the most common type of helical gear. It produces a wedging action by moving the tooth axis in the direction of the cross-axis. There are two ways to mesh a helical gear: by putting it into a crossed configuration, and by putting it into a radial configuration.